Uniform pressure absorption evaporator



May 27, 1952 w. EDEL UNIFORM PRESSURE ABSORPTION EVAPORATOR 2 SHEETS-SHEET 1 Filed Aug. 24, 1948 INVENTOR.

WALTER L. EDEL ATTORNEY y 27, 1952 w. EDEL 2,598,240

UNIFORM PRESSURE ABSORPTION EVAPORATOR I Filed Aug. 24, 1948 Y 2 SHEETS-SHEET 2 k), /7Q 22:: 26a 30 11 kg {PW-" 22 26a.

, INVENTOR. WALTER L. EDEL BY MWM A TTORNEY '1 5 4 I F i 5 a Patented May 27, 1952 UNITED era-res UNIFORM ,PBESSURE ABSORPTION EVAPORATOR Applicationiiugust 24, 1 948, Serial No.4 5,8 56

it is desirable to maintain, under no-loadconditions, a 1 to 1.5 cubic'foot' freezing compartment and"a '7 :cubic footchilling "compartment at -air temperatures which do notexceed the generally recommended maximums 'of 10 anddt Rrespectively.

It has been found extremely difficult :to achieve a performance of this character in absorption-refrigerators of the uniform pressure type. This may be illustrated by reference to the performance of what'is undoubtedly the'best absorption refrigerator of the uniform pressure type thus far developed and marketed.

This particular refrigerator comprises: (-1) a refrigerator cabinet having afood' storage chamber divided into a freezing compartment approximating 1.1'cubic feet and a chilling compartment approximating 7.2 cubic feet; (2) an evaporator in the form of an elongate tube having its colder section, which is hereinafter called the freezing section, arranged to refrigerate the freezing compartment, and'its warmer section, which is "hereinafter called the chilling section,

arranged to refrigerate the chilling compart- U ment; (.3) a heat exchanger placing the purified hydrogen gas, flowing upwardly from the absorber to the evaporator, in heat exchange relationship' with the heavy mixed'gas andresid-ual liquor flowing downwardly "from the evaporator outlet to the absorber; (4) a liquid tube conducting the residual liquor from the evaporator outlet to the heat exchanger; and (5) a gas tube separately conducting the heavy mixed gas from the evaporator outlet tothe heat exchanger, this tube being arranged in direct heat exchange' relationship with the incoming liquid ammonia feed lineto precool theammonia.

With a room temperature of 110 F., this refrigerator maintains the freezing compartment at a no load air temperature of 20 t0'24" which exceeds the recommended maximum by l0 to 14 F.

The principal object of this invention is to effect a substantial improvement in the performance of absorption refrigerators of theuniform pressure type and, more particularly, to secure, in such type of refrigerator, freezing compartment temperatures well within the presently recommended maximum.

Sfilajms. (Cl. Ghee-119.5)

Another object is toachieve thecprincipallobr jective without any offsetting disadvantage such as an objectionable change in .overall size ..or weight, in manufacturing or operating costs,-,.or in overall operation.

A further object is to providean extremely simple means for effecting a substantial improvement in the performance of -thisxtyp (if-refrigerator -and,more particularly, fonproducingand maintaining, in the freezing compantment,.=.tem.- peratures low enough to insure'highl-y satisfac tory operation under all normally encountered conditions. I

I have found-that a substantial-reduction in the freezing compartment air-temperaturemay be effected simply by placing either-or :both .of the incoming hydrogen and ammon-ia feed lines going to the evaporator indirect physical shea-t exchange relationship with the chillingsection of the evaporator so as to precool either or both of these fluids before they enter'the evaporator. In this way the introduction of heatinto the freezing section is minimized-and the securementof lower freezing temperatures promoted.

Off hand, one mght expect-that the-introduction of heat into-the evaporator chilling section would deleteriously. affect its operation and bring about substantially higher air temperatures/in the chilling compartment. Surprisingly, I however, the pro-cooling of the incoming hydrogen and ammonia in the chilling section doe'sriotappear to do so. 1 It'maybe that th'e-produet ion of substantially lower operating temperatures in the freezing section resultsm ths-production, in the chilling section, of better operating conditions which partly or wholly offset any disadvantage arising from the introduction of heat into the chilling section. Furthermore-since the heat-introduced into the chilling section at anyone point, and particularly at the point where the relatively warm feed lines first come into contact with the chilling section ofthe-evaporator, -is-at a higher temperaturethantlje temperature prevailing at that point within the evaporator on-ill;- ing section, I have reason to believe' that the thermal efficiency of the chilling section, and the operating efiiciency of the refrigeratmg mechanism as a whole, is substantially improved and this improvement may the sufiicient to oiiset, or even outweigh, any disadvantage arising from the introduction of heat into the? chilling section.

Whatever the reason may be, :I have-note perienced an-y diiiiculty in obtaining chilling compartment air temperatures below the 'rcommended maximum. For example, with 11a refrigerator having freezing and, chilling compartments of 1 and '7 cubic feet respectively, and with a room temperature of 110 F., I have been able to secure freezing and chilling compartment air temperatures of and 44 F. A performance of this character compares favorably with any of the presently available household refrigerators regardless of type.

The invention is' illustrated in the accompanying drawings wherein:

Figure 1 is a side View of one embodiment of the invention, the refrigerator cabinet being shown more or less in outline;

Figure 2 is a rear view of Figure l with the insulation removed;

Figure 3 is a top view of Figure 2 with the insulation removed;

Figure 4 is a schematic View illustrating the arrangement of the parts forming the evaporator, heat exchanger, hydrogen gas feed line and the ammonia feed line;

Figure 5 is a section taken along line 5-5 of Figure 2 illustrating how the tubes are bonded; and

Figure 6 is a schematic view of a modified form of evaporator.

The uniform pressure absorption refrigerator, illustrated in Figures 1-4, is assumed to be, and is explained as, one utilizing an ammonia, hydrogen and water system,- although any other suitable system may be employed. As illustrated, this refrigerator comprises: a cabinet; and a refrigerating mechanism.

The cabinet I has: an insulating front door 2 providing access to an unobstructed freezing compartment 3, formed by appropriate walls including rear and bottom walls 4 and 5, and an unobstructed chilling compartment 6, formed by appropriate walls including rear wall 'i, the walls 4, 5 and 1 being composed of heat conductive material preferably metal; and suitable heat insulating material 8 completely surrounding each compartment except at their open door-insulated front ends.

The refrigerating mechanism comprises: a generator 10; an air cooled ammonia condenser ii; an air cooled absorber l2 a strong and weak liquor heat exchanger not shown; a receiver l3; and an elongated tube extending upwardly from the absorber and then downwardly back to the absorber to form an evaporator, a heat exchanger between the evaporator and the absorber i2, and the endless gas circuit required for the operation of the absorber, heat exchanger and evaporator.

The evaporator has two sections, namely: a freezing section outside of the freezing compartment 3 but in direct physical heat transfer relationship with its rear and bottom walls 4 and 5; and a chilling section outside of the chilling compartment but in direct physical heat transfer relationship with its rear wall I. This evaporator is one in which the hydrogen gas and ammonia liquor are initially fed to opposite (lower and upper) ends of the freezing section to flow in countercurrent relationship and the resulting mixed gas and partially evaporated ammonia liquor are finally fed to the upper end of the chilling section to flow in concurrent relationship. The paths of these materials are explained in the following paragraphs in connection with Figure 4.

As shown in Figure 4, the gas, in flowing upwardly from the absorber and downwardly back to it, passes through the following sections of the they enter the evaporator.

elongated tube: an absorber outlet section l5, heat exchanger section l6, precooling section I! and connector section it, all for the upward flow of relatively pure hydrogen gas; evaporator freezing sections 19 and 2B for the upward flow of mixed gas; and connector section 2|, evaporator chilling section 22, heat exchanger section 23 and absorber inlet section 24, all for the downward flow of the heavy mixed gas.

The liquor flowing from the ammonia condenser I, passes through the following sections: downwardly through section 25 of the ammonia feed line; upwardly through precooling section 26 and section 21 of that feed line to feed point 28 where it enters the upper end of the freezing section 20 adjacent the connection of that section to the connector section 2i; downwardly through the freezing sections 26 and I9 to the exit point 29 where it leaves the freezing section; downwardly through transfer line 30 to the feed point 31 where it enters the upper end of the chilling section 22 adjacent the connection of that section to the connector section 2!; and thence downwardly through chilling section 22, heat exchange section 23, absorber inlet section 24 to the absorber 12.

It will now be appreciated that the incoming ammonia is fed to the upper end of the freezing section while the incoming hydrogen is fed to the lower end of the freezing section so that these fluids flow through the freezing section in countercurrent relationship to each other. However,

both of these fluids are fed to the upper end of the chilling section to flow in concurrent re lationship therethrough. It will also be understood that the ammonia is only partially evaporated in the freezing section, its evaporation being completed, or substantially completed, in the chilling section.

In the specific embodiment shown in Figs. 1-3, the freezing section 20 is L-shaped so that it extends horizontally across the upper part of the rear wall 4 and thence vertically downward along one side edge of that wall to the bottom edge where it connects into the freezing section l9 which extends in a serpentine manner along the bottom wall 5 to the exit point 29. The chilling section 22 is U-shaped extending horizontally along the upper edge of rear wall I and thence downwardly along the side edge to a point adjacent the central horizontal level of the chilling compartment 6 and thence horizontally across the rear wall I to the opposite side edge where it joins heat exchanger section 23 which slopes rearwardly away from the rear wall of the chilling compartment.

In accordance with my invention, either or both of the incoming hydrogen gas and ammonia liquor feed lines are placed in precooling relationship with the evaporator chilling section 22 in order to precool these incoming fluids before Accordingly, I show the hydrogen precooling section I? and ammonia precooling section 28 both in direct physical contact with the evaporator chilling section 22. Preferably also these precooling sections H and 28 are arranged with their fluids flowing in the same direction but in counterfiow relationship to the gas and liquid flowing through chilling section 22.

The tubular sections forming each part of the evaporator are soldered, or otherwise bonded, directly to the adjacent wall. Thus, freezing section I9 is bonded to the bottom wall 5 of the freezing compartment, while freezing section 20 and "chiilmgisectioni'flrarexrespectively bonded to rear walls 4 and I. The Walls 4,, '5 and Ti may either-form part oft-he compartments 3 and B or they may be separate walls which, when the refrigerator is assembled, are brought into good heattransferrelationship with the corresponding walls of the food compartments. As indicatedin Figure 5, only the evaporator tubes are bonded to thefood-compartmen-t walls. The precooling sections -17 andifi'are bonded to-the-chi-lli-ngsection 2. 2 but are spaced from the rear wall 1 so as to -avoid-the direct transfer of heat irom either of these incoming feed linesections to rear wall 1.. With an=arrangementeof the foregoing character operating in a room temperature of 3.00" I I have-achieved a performance of :the following character: hydrogen leaving the absorber at a temperature of 118 F.is cooled in the heat exchanger-section 46. to about 57 F. then in the precooling section I"! to .a temperature approximating 177 F., while ammonia leaving the condenser at a temperature approximating 128 F. is precooled in section 26 to a temperature approximating F. This ammonia, entering freezing section 25 at 15 downwardly through freezing sections 2i] and 19. In so doing,ii't cools itself, by such evaporation, to a muchlow'ertemperature by the time it reaches the ammonia exit point '29 at the lower end of the freezing .se'ction. This exit point '29 corresponds to the point of initial refrigeration because'iitlis the area where the incoming precooled "hydrogen first strikes the evaporating stream "of armnonia. The low temperatured hydrogen andthes'till'lower temperatured ammonia'thuscooperate to promote the achievement of anextremely low temperature adjacent this point of initial refrigeration. The operating temperature of the freezing section of the evaporator naturally rises progressively through sections' 19 and but remains below 0 at the "point Where these sections join and reaches a temperature approximating 3 F. at the upper end 'of'sec'tionzfl where the outgoing'mixed gas entersthe connector 2 I. 'Withthesetemperature conditions, the freezing section produced an 'air temperature approximating? F. in a 1% cubic foot freezing compartment.

The "performance of the chilling section, under the sameconditionsofoperation, is indicated by evaporates as it passes the chilling 'tube temperatures which approximate 8 F. at the upper end of the chilling tube, 22 F. at its center, and 491 at its lower end. With .these temperature conditions, the chilling se'c'tion produced an air temperature approximating 43 F. in a 7 cubic foot chilling compartment.

The performance of the refrigerator at room temperatures of 73.5 F. and 110 F. is shown by the following tabulation:

(a)'-Room temperature -73}-F 110F (t) .Kmmonialeaving condenser 11. 94F... ,128FZF (c) l lydrogen'leaving absorber 12 787F ,118 1 (d) Hydrogcn dropinprecooling-section '26'F. to be-- 57 F. to

sl7fromentry to exit (exit tempera- -loxv. O. :l7E-F. 'tureassumed to 'be same as (a) I below).

(a) Ammoniadrop in precooling section. 434%: to be-i P123" ,to

26Jfrom e'ntry'to eXit(entrytemlow 0. ,15 F apetatureassumedutobe same as (b) above and exit temperature assumed same as (2') below).

( f) Chilling tube drop from outlet to F. to be- 49 F. to 8 inlet ends. low 0. F.

(g) Hygrogcn entering freezing section below 0 17 F.

(h) Mixed gas leaving freezing section 20. below 0.. 3 F.

(1') Anamonie entering freezing section below 0 15 F.

(j) Freezing compartment air minus 9 F.. 5 F.

(It) Chilling compartment air 25 F 43 F.

In connection with the operation eflthisare frigerator in a room temnetaturegof 1.10 5111. 10.1 example, it will be noted thatrata pcintxcorresponding :to the outlet tend 1.0;? the chilling tube, the chilling tube temperature is 49 i F. the ammonia and hydrogen tempe atures a pective1yare-79" zand 8- ieher- W these temperature differentials, heat of th ncoming ammonia and hydrogen should c use 5151-18 liquor in the chilling tube"to evaporatevigorous- 1y. This vigorous :evapora-tionno doubt pccurs throughout the length -of the chilling .tubefibecause the chillingtube temperature-attire i at end is also eppreciabiy lower-than the comin hydrogen and ammonia sat th o f i fipm flm point. The vigorous evaporation, thusoccasioned in the chilling :section, .should increase 1 thermal efiiciency of that section and :may crease the operating .efiiciency vfctl-ie reirigeratm mechanism as-awwhole. 'lt is- ,ereforaLimesible that these increases effect, in -zthe operation {of the :mechanism, an improvement which is :50 sub-- stantial that it either offsetsonou tweighs :any flisadvantage- .arisi-ng from :the introduction of zheat i into the chilling section.

:In %-,the modification -:show.n in Fi ure i6, iammania and hydrogen are both tied to thazupper end :of the freezing section to chew concurrently therethroughand thenceito opposite endsofithe chilling section to fiowuin .countercurrent relationship. :I-Iere thegas-circuit,:procee'dingzinlthe direction of gasflow,..includesi: :absorher ioutlet sectionilt5; heat exchangersection 1. 6; :precooling section i'l'fl'aggconnector section 18a; fIEGZGI'iSGC- tions 20a; and 19a; :connector section "1211a; chilling section 22a; heat exchanger .section 23; and absorber inlet section 24. The liquor from the ammonia condenser passes "through-the following sections: section .25; :precooling section 26a and section email in the feed-line; freezing sections 20a; and l-=9a,;'-trans'fer tube 30 chilling section 22a; and residual "liquor tube 32 "which connects the lower-end *of section 22a into the heat exchanger section 23.

'In both of the arrangements shown in Figures 1-4 and 6, the chilling se'ction is seriatlly connected to one -endof the freezing section 'by a gas connector containing substantiallymo -liquid ammonia and in which at evaporation takes place. The connectorZ-i of Figures 14-isnot in "heat exchange relationship with any part "of the gas circuitbutin-Figure 6 the 'corresponding connector "2-lais "in heat exchange relationship with both of the "incoming gas and liquid "ammonia feed lines. In both arrangements "also, the precooling "section of the incoming hy 'drogen line "is connected to the inlet -end -of the freezing section icy-a connector in which-no evaporation occurs. Accordingly, both ,arrangements involve conduit 'means forming evaporator freezing and :chilling sections'conheated in series by a gas "fiow'connector, the freezing section having a gas inlet ancl a' zliqui'd refrigerant feedpoint :and'the chilling section a-mixedjgas outlet withboth sections "and "the gas flow connector :cooperating "to provide a gas path forthe flow of inert gas from 'thegasinlet serially through the freezing section, the connector and the chilling section to the gas outlet and a path for the flow of liquid refrigerant from the feed point through the freezing section and thence through the chilling section.

This application is a continuation in part of my application Serial No. 708,603 filed Novem her 8, 1946, now abandoned.

I claim as my invention:

1. In a refrigerator of the uniform pressure absorption type: an insulated cabinet providing separate insulated freezing and chilling compartments; conduit means forming an evaporator freezing section in heat exchange relation to said freezing compartment and a chilling section in heat exchange relation to said chilling compartment, said sections being connected in series by a connector for the flow of gas and by a separate transfer line for the flow of liquid refrigerant, the freezing section having a gas inlet and a liquid refrigerant feed point, and the chilling section having a mixed gas outlet, both of said sections cooperating to provide a gas path for the flow of gas from the gas inlet serially through the freezing section, the connector and the chilling section to the gas outlet and providing a liquid path for the flow of liquid refrigerant from said feed point serially through the freezing section, the transfer line and the chilling section; and conduit means forming separate passages for the separate flow of incoming liquid refrigerant into said feed point and of incoming inert gas into said gas inlet, both of said incoming passages being elongated and arranged in direct physical heat transfer relationship along a portion of their respective lengths with said chilling section.

2. An evaporator as specified in claim 1 wherein the direction of flow of liquid refrigerant and inert gas in the freezing and chilling sections are respectively countercurrent and concurrent.

3. In a refrigerator of the uniform pressure absorption type: an insulated cabinet interiorly providing insulated freezing and chilling compartments which are also separated from each other by insulation, each compartment having a heat-conductive wall presenting an inner face exposed to its compartment space and an outer face exposed to its compartment insulation; an absorber; a closed-circuit conduit connected between the absorber inlet and outlet for the circulation of inert refrigerant gas and including a freezing section in direct physical heat transfer relationship with the outer face of said freezing compartment wall to constitute a freezing evaporator, a chilling section in direct physical heat transfer relationship with the outer face of said chilling compartment wall to constitute a chilling evaporator, and a gas feed section for carrying inert gas from the absorber outlet to the freezing evaporator inlet; and supply line means for supplying evaporating liquid refrigerant to said freezing and chilling evaporators, said means including an elongate tube in the freezing evaporator supply line; said tube and said gas feed section both being in direct physical heat transfer relationship along a portion of their respective lengths with said chilling evaporator for precooling purposes.

4. In the refrigerator of claim 3 wherein: the direction of flow of liquid refrigerant and inert gas in the freezing and chilling sections are respectively countercurrent and concurrent.

5. In the refrigerator of claim 3 wherein: the precooled portion of said liquid refrigerant tube is spaced from the outer face of said chilling compartment wall.

6. In the refrigerator of claim 3 wherein: the precooled portion of said gas feed section is spaced from the outer face of said chilling compartment wall.

7. In a refrigerator of the uniform pressure absorption type: an insulated cabinet; an insulated partition dividing the interior of said cabinet into freezing and chilling compartments, said chilling compartment having a heat-conductive liner; an absorber; a closed-circuit inert refrigerant gas conduit having, for the flow of gas between the absorber outlet and inlet, elongate gas feed, freezin connector, chilling and return sections, the feed section extending from the absorber outlet to the freezing section inlet and having relatively lower and upper elongate portions, the freezing section extending to the connector section inlet and being outside of the freezing compartment but in direct heat exchange relationship therewith to constitute a freezing evaporator, the connector section extending to the chilling section inlet, the chilling section extending tot-he return section inlet and being outside of the chilling compartment but in direct physical heat exchange relationship with said liner to constitute a chilling evaporator, and the return section extending from the chilling evaporator outlet to the absorber inlet; and supply line means for supplying evaporating liquid refrigerant to the freezing and chilling evaporators for flow therethrough, including an elongate tube in the freezing evaporator supply line; said elongate refrigerant liquid tube and the upper portion of said refrigerant gas feed section both being in direct physical heat exchange relationship along their respective lengths with the chilling evaporator for precooling purposes but spaced from said liner; and said return section and the lower portion of said feed section both being in direct physical heat exchange relationship with each other but spaced from said liner.

8. In the refrigerator of claim 7 wherein: the direction of flow of liquid refrigerant and inert gas in the freezing and chilling sections are respectively countercurrent and concurrent.

WALTER L. EDEL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS- Number Name Date 1,849,685 Munters Mar. 15, 1932 2,059,877 Kogel Nov. 3, 1936 2,131,782 Maiuri -l Oct. 4, 1938 2,181,376 Lynger Nov. 28, 1939 2,345,505 Siedle Mar. 28, 1944 2,377,000 Gerber May 29, 1944 2,4017 33 Ashby Sept. 17, 1946 2,468,104 Phillips Apr. 26, 1949 2,489,752 Coons Nov. 29, 1949 

